In recent years, charging of storage batteries installed in a vehicle such as an electric vehicle using a power supply of a house (house of the owner of the vehicle) has been in practice. Since the power supply of a house supplies power to various electric devices such as an air conditioner, an overcurrent flowing through a power supply circuit may be caused by, for example, an increase in the number of electric devices in use. When an overcurrent occurs, the power supply circuit is shut off to stop supply of the power to the electric devices, thus making all the electric devices temporarily unusable.
Conventionally, electric device systems configured to reduce a current amount according to a decrease in a receiving voltage have been known as a method of preventing an overcurrent flowing through a power supply circuit in a house (for example, Patent Literature (hereinafter, abbreviated as PTL) 1). In an electric device system of PTL 1, when a decrease in a receiving voltage is detected by a voltage detector, a current amount in the entire system is reduced by controlling a power converter according to this decrease.